The present invention relates generally to data communications. More particularly, the present invention relates to physical-layer device management for network switches.
It is often desirable to manage a network switch remotely, that is, from a location other than the location of the network switch, generally by reading and writing memories, such as configuration registers and memories storing address and management information databases, in the network switch.
Conventional techniques for remote management of network switches include implementing a unit that includes a central processing unit (CPU) connected to the network switch. Management frames are sent to the CPU, which manages the network switch. One disadvantage of this approach is the cost of the CPU, especially when the location of the network switch, for example outside a customer's home, requires the CPU and any associated components to be implemented according to industrial temperature standards.
Once the CPU receives management frames, the CPU reads and writes registers and memory inside the attached network switch device using a local interface. One conventional technique for this ‘CPU to register’ access is a high speed bus interface like PCI (Peripheral Component Interconnect). One disadvantage of this approach is the cost of the device pins associated with such buses.
One conventional technique to save pins for the local interface of network switches employs an existing serial interface such as the System Management Interface (SMI) to manage the network switch. SMI requires only two pins that can be shared between many devices, but has comparatively slow performance. However, as the performance and complexity of current network switches has grown, so have the switch databases, which are now so large that the SMI interface is now considered too slow to transfer such large amounts of data. For example, to read an 8 k entry address database over an SMI interface may require approximately 25 seconds depending upon the design. Furthermore, customers are reading management information frequently, for example to determine utilization rates.